Surprisingly, not a sky replacement; it's a very, very average short level with a building and some imps that pop out of the ground. It's hard to believe this was done in 2003 (perhaps it wasn't), because it's vintage 1995. Inconsequential.

At first, i thought it was a texture replacement for the sky. But thankfully it was just a level. The level has somewhat good detail and is a bit challenging. Just before you get the red key, you get stuck in this dark room and the only way to get out is to keep pressing the use key on the wall and hope you find an exit. The map itself was decent. This map is fun to play when you're bored. 3/5 *** - DoomGeek101